A technique for easily making modifications to a graphical user interface (GUI). XML files each containing different rules for making a tree display are easily written by code developers. The files are merged into a document object model (DOM) stored in memory. The GUI display presentation can thus be easily updated by the code developers by modifying the rules stored in the DOM by merging additional XML files containing rule additions, deletions and/or modifications into the DOM. The DOM is parsed for certain object classes for which object instances are needed. The object instances having certain display properties are retrieved from the system or network with which the GUI is operative and are combined with certain display attributes or display rules stored in the DOM. The object instances including their display properties and attributes are returned to the GUI to be displayed on the terminal screen in accordance therewith.